Upper airway myofunctional exercise is a training technique for patients with obstructive sleep apnea involving isotonic and isometric exercises of the upper airway muscles involved in obstructive sleep apnea designed to strengthen upper airway myofunction and improve patients' symptoms. The objective of this review was to evaluate the safety and effectiveness of upper airway myofunctional exercise. A literature search was conducted using 8 Korean databases, Medline, Embase, and the Cochrane Library. Of the 197 articles that were initially identified, 8 studies were included in this review. The results show that upper airway myofunctional exercise improved the apnea-hypopnea index in adult patients, and that it led to improvements in symptoms and upper airway myofunction when administered alone or after adenoidectomy in pediatric patients. On the basis of the current data, upper airway myofunctional exercise can be considered a safe and effective technique for patients with obstructive sleep apnea.